KE Headers on 525 EFI
11-21-2018, 06:47 AM
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KE Headers on 525 EFI
Has anyone swapped out the CMI/Merc exhaust that comes on the 525 with the Thunder and Lightning exhaust from Diamond? I just bought a boat with 525's in it, and I really don't like the idea of these headers on the engines. Yes I know the heads will need to be drilled and tapped, but other than that, would any other modifications need to be done?
11-21-2018, 10:59 AM
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Has anyone swapped out the CMI/Merc exhaust that comes on the 525 with the Thunder and Lightning exhaust from Diamond? I just bought a boat with 525's in it, and I really don't like the idea of these headers on the engines. Yes I know the heads will need to be drilled and tapped, but other than that, would any other modifications need to be done?
11-21-2018, 11:10 AM
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Not sure why you would have to drill and tap your heads, I was going to use them on my boat but the transom holes needed to be moved so I went with Stellings. The only concern would be adequate water flow and would suggest a water pressure gauge if you don't already have them as the KE's are aluminum. I bought the KE's because the power curve was better than the Stellings but, redoing the transom wasn't worth it to me. I have been told they sound great and I like they way they look (sleeper). If you go that route I would be interested in how you like them. Oh, salt away flush after every use since they are aluminum.
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11-21-2018, 12:29 PM
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Not sure why you would have to drill and tap your heads, I was going to use them on my boat but the transom holes needed to be moved so I went with Stellings. The only concern would be adequate water flow and would suggest a water pressure gauge if you don't already have them as the KE's are aluminum. I bought the KE's because the power curve was better than the Stellings but, redoing the transom wasn't worth it to me. I have been told they sound great and I like they way they look (sleeper). If you go that route I would be interested in how you like them. Oh, salt away flush after every use since they are aluminum.
I’ve used them on two other boats, and they are an awesome header, and yes they sound great. On my first boat, with a high reving 439 bbc I picked up 2 mph over Stainless Marines.
11-21-2018, 12:43 PM
#6
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Go with the Stainless Marine setup. It's not as pretty as full headers, but they are a proven product with plenty of happy customers.
AT installed a set on a 37AT with 600SCis and not a single change in performance. (That boat is in Indiana now.) They aren't as pretty, but I'll take reliability over pretty any day of the week and twice on Sunday.
If it were me, I would paint the 'manifold' portion silver to match your boat, and I think the contract with the Mercury blue would look awesome. And it's less cleaning/polishing to do back there too.
Clark aka "crb76" was the original owner of your boat. He's one of my closest friends and posted a fair amount here on OSO when he first got it. His dad, "chuck beecher" here on OSO was also quite active at the time. Chuck purchased a 32' from Pat/AT way back in the day, so it was awesome when Clark purchased a 37'. Your boat has been 90.1mph with a set of Herring high end props in it back in the day. It's also the smoothest riding and most solid 37' AT I've been in to date. I have a lot of hours driving and riding in that boat from when he owned it from new.
You have a helluva boat. I was quite tempted on purchasing when it came up for sale, but I am now having to much fun racing cars.
AT installed a set on a 37AT with 600SCis and not a single change in performance. (That boat is in Indiana now.) They aren't as pretty, but I'll take reliability over pretty any day of the week and twice on Sunday.
If it were me, I would paint the 'manifold' portion silver to match your boat, and I think the contract with the Mercury blue would look awesome. And it's less cleaning/polishing to do back there too.
Clark aka "crb76" was the original owner of your boat. He's one of my closest friends and posted a fair amount here on OSO when he first got it. His dad, "chuck beecher" here on OSO was also quite active at the time. Chuck purchased a 32' from Pat/AT way back in the day, so it was awesome when Clark purchased a 37'. Your boat has been 90.1mph with a set of Herring high end props in it back in the day. It's also the smoothest riding and most solid 37' AT I've been in to date. I have a lot of hours driving and riding in that boat from when he owned it from new.
You have a helluva boat. I was quite tempted on purchasing when it came up for sale, but I am now having to much fun racing cars.
Last edited by Sydwayz; 11-21-2018 at 12:50 PM.
11-21-2018, 01:49 PM
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Sydwayz- Yes I think "Stealin' Thunder" is one of the nicest looking 37's I've seen. I wasn't really in the market for a new boat when I first saw it, but it was in near showroom condition, and I absolutely loved everything about it. Well other than the headers that 525's come with. I knew I wouldn't find another one like this anytime soon, so I jumped on it. Everything was finalized this morning! I'm glad you have good things to say about the boat.
I'm really leaning toward the Thunder and Lightning setup as I've run them back to back on NA boats and did see an improvement over the Stainless Marine manifolds. The Stainless setup is nice and reliable though. If I have to relocate things with the Thunder and Lightning headers, I'll go the stainless route. And yes, I will be having them powder coated silver, I agree it would match the boat and look great.
I'm really leaning toward the Thunder and Lightning setup as I've run them back to back on NA boats and did see an improvement over the Stainless Marine manifolds. The Stainless setup is nice and reliable though. If I have to relocate things with the Thunder and Lightning headers, I'll go the stainless route. And yes, I will be having them powder coated silver, I agree it would match the boat and look great.
11-21-2018, 02:23 PM
#8
FACTORY CMI headers that came on 525s are the issue. CMI makes better products. But the headers that Merc spec’d for the factory package were usually just good enough to last the warranty period. CMI got the bad wrap for such, but it’s 100% Mercury’s fault. CMI wanted to put better headers on there originally but Mercury price/volume pressured them to the lesser product.
11-21-2018, 02:56 PM
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I talked with Bill today, outside of drilling the standard bolt pattern in the heads, he said everything else will be exactly as it is now. I've had custom tales made before for K/E headers. With the flanges you can buy from Bill, it's mostly just a straight back set up, at least my last set was. I think I may go with Teagues 450 switchable tips so I can retain the selectable exhaust. If that is the case, the tails will be pretty short.
